arXiv subjects

Samer Alhaddad

Publications and source records attributed to Samer Alhaddad.

3 recordsLinked to original sources

arXiv2024

Full Field Transmission Tomography (FFOTT) for imaging extrachromosomal circular DNA (eccDNA) in cancer cell nuclei

Detecting the specificity of cancer cells to distinguish them from normal ones is an important step in the general framework of cancer diagnosis. A routine example of such diagnosis in cancerous tissues implies using microscope analysis of fixed, paraffined, and colored slices such as the H&E stain (1). Such a method, which takes place after surgery, is based on carefully analyzing the cell's size and shape. Often, this approach is performed in parallel with more modern genetic tests. Recent research has hypothesized that extrachromosomal circular DNA (eccDNA) could be considered a new hallmark of cancer (4). Thus, this research aims to check if using a simple, label-free microscope dynamic analysis performed on living cancer cells would allow efficient and simpler detection of cancer cells.

physics.med-ph↗

arXiv2023

Comparative analysis of full-field OCT and optical transmission tomography

This work compares two tomographic imaging technologies, time-domain full-field optical coherence tomography (FFOCT) working in reflection and optical transmission tomography (OTT), using a new optical setup that combines both. We show that, due to forward-scattering properties, the axial sectioning and contrast in OTT can be optimized by tuning illumination. The influence of sample scattering and thickness are discussed. We illustrate the comparison of the two methods in static (morphology) and dynamic (metabolic contrast) regimes using cell cultures, tissues and entire organisms emphasizing the advantages of both approaches.

physics.optics↗

arXiv2022

Label free optical transmission tomography for biosystems: Intracellular structures and dynamics

There is an increasing need for label free methods that could reveal intracellular structures and dynamics. In this context, we develop a new optical tomography method working in transmission - Full-field optical transmission tomography (FF-OTT). The method can measure the forward scattering signals and reveal the metabolic time-dependent signals in living cells. FF-OTT is a common path interferometer taking advantage of the Gouy phase shift - a π phase shift that the light wave experiences around the focus. By modulating position of the focus one can alter the phase of the scattered light. Demodulation of images with different phases rejects the background and enhances the light from the depth-of-focus, thus producing an optical section. We test FF-OTT by imaging single-cell diatoms and ex vivo biological samples. In fresh samples, we show that the intracellular motions create visible intensity fluctuations in FF-OTT so that the method is able to reveal a metabolic dynamic contrast. FF-OTT was found to be an efficient label free technique that can be readily implemented thanks to a robust common-path speckle-free interferometer design using an incoherent light source.

physics.optics↗